Industrial doors in industrial or commercial buildings separate zones of different temperature or humidity conditions or prevent noise propagation between the zones. One common form of industrial door is a roll door in which a fabric door panel is coiled on a drum located above the header of the doorway. A drive mechanism is connected to the drum, and operation of the drive mechanism in one direction will uncoil the door panel to move the panel to a closed position, while operation of the drive mechanism in the opposite direction will act to coil the panel on the drum and move the door panel to the open position.
A typical drive mechanism for an industrial door includes a clutch which can be manually operated to disconnect the drive. A clutch is required in order to provide manual operation of the door in case of fire or a power outage or during maintenance or installation of the door.
With a conventional clutch as used with an industrial door, the motor will continue to operate when the clutch is disengaged. If an attempt is made to engage the clutch while the motor is operating, jamming or shearing of the components of the drive system can frequently occur. Therefore, there has been a need for a drive mechanism for an industrial door in which disengagement of the drive system will also act to shut off power to the drive source or motor.